CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES

Components for cash, cash equivalents and marketable securities (in millions):



September 30, 2012	Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Cash	$	11.3	$	—	$	—		$	11.3
Money market funds and other securities	16.2		—		—			16.2
Cash and cash equivalents	27.5		—		—			27.5
U.S. government and agency securities	329.5		2.5		—			332.0
Foreign government bonds	44.5		1.0		—			45.5
Asset-back securities	101.4		0.6		—			102.0
Mortgage-back securities	118.2		1.2		(0.1		)	119.3
Corporate notes and bonds	530.4		9.6		(0.1		)	539.9
Municipal securities	19.3		0.1		—			19.4
Marketable securities	1,143.3		15.0		(0.2		)	1,158.1
Total	$	1,170.8	$	15.0	$	(0.2	)	$	1,185.6



December 31, 2011	Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Cash	$	62.1	$	—	$	—		$	62.1
Money market funds	40.1		—		—			40.1
Cash and cash equivalents	102.2		—		—			102.2
U.S. government and agency securities	292.5		3.4		—			295.9
Foreign government bonds	24.9		0.5		—			25.4
Asset-back securities	58.2		0.1		(0.3		)	58.0
Mortgage-back securities	124.1		1.1		(0.3		)	124.9
Corporate notes and bonds	518.0		7.0		(2.4		)	522.6
Municipal securities	11.8		0.1		—			11.9
Marketable securities	1,029.5		12.2		(3.0		)	1,038.7
Total	$	1,131.7	$	12.2	$	(3.0	)	$	1,140.9

Activity for marketable securities (in millions):



	Three Months Ended September 30,				Nine Months Ended September 30,
	2012		2011		2012		2011
Proceeds from sales and maturities	$	271.1	$	238.2	$	701.5	$	697.2
Gross realized gains	2.2		2.9		5.8		6.2
Gross realized losses	0.4		0.3		1.2		2.0
Other-than-temporary impairments on investments	—		1.5		0.3		1.5

Of the marketable securities on hand at September 30, 2012, 3.7% mature in 2012, 27.1% in 2013, and 69.2% thereafter.

Investments with continuous unrealized losses (in millions):



	Less than 12 months					Greater than 12 months
September 30, 2012	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Total Fair Value		Total Unrealized Losses
Mortgage-backed obligations	$	32.7	$	(0.1	)	$	4.3	$	—		$	37.0	$	(0.1	)
Corporate notes and bonds	14.8		—			1.3		(0.1		)	16.1		(0.1		)
Total	$	47.5	$	(0.1	)	$	5.6	$	(0.1	)	$	53.1	$	(0.2	)



	Less than 12 months					Greater than 12 months
December 31, 2011	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Total Fair Value		Total Unrealized Losses
Asset-backed obligations	$	31.7	$	(0.1	)	$	1.1	$	(0.2	)	$	32.8	$	(0.3	)
Mortgage-backed obligations	35.1		(0.2		)	1.9		(0.1		)	37.0		(0.3		)
Corporate notes and bonds	137.4		(2.4		)	1.0		—			138.4		(2.4		)
Total	$	204.2	$	(2.7	)	$	4.0	$	(0.3	)	$	208.2	$	(3.0	)

Unrealized losses from fixed-income securities are primarily attributable to changes in interest rates. Management does not believe any remaining unrealized losses represent other-than-temporary impairments based on our evaluation of available evidence as of September 30, 2012.